Spring force actuated - Door locked
... what is the difference between a process guard locking and a safety guard locking?
DIN EN ISO 14119:2014 describes the function of an interlocking guard with guard locking.
Its purpose is to hold a guard in the closed position so that:
- the machine cannot be in operation if the protective device is not closed and locked
- the guard remains locked until there is no longer any risk of injury
While a process guard locking is open without voltage according to the open-circuit current principle, a safety guard locking works according to the closed-circuit current principle and is therefore closed without voltage, as the actuator is held in place by spring force. On the other hand, an electromagnet is used for a process guard locking. The door, or a similar access, is thereby kept closed by magnetic force. If the magnet is no longer energized, the process guard locking can open immediately.
Energy ON unlocked - Door unlocked
Energy ON actuated - Door locked
Energie OFF unlocked - Door unlocked
Due to these requirements, it is important to differentiate between a process guard locking and a safety guard locking,
because there are significant differences in the mode of operation.
For example, if the system loses power due to a power failure, the door could be immediately opened while movements inside the system are still running out. For this reason, the run-down time as well as the calculation of the safety distance to the danger point (see page 6/7) must always be taken into account when process guard locking devices are used.
In simplified terms, it can be said that safety guard locking devices are used for systems with a long run-down time and process guard locking devices are used for systems with a short run-down time. Specifi cally, the C standard for packaging machines, DIN EN 415-5:2010-04 in Section 184.108.40.206.7, defi nes the stopping time more precisely. If the system comes to a standstill within one second after opening the guard, a process guard locking can usually be used.